Phylogeny of the Tachycineta genus of New World swallows: Insights from complete mitochondrial genomes

The Tachycineta genus of swallows is comprised of nine species that range from Alaska to southern Chile. We sequenced the entire mitochondrial genome of each member of Tachycineta and generated a completely resolved phylogenetic hypothesis for the corresponding mitochondrial gene tree. Our analyses confirm the presence of two sub-clades within Tachycineta that are associated with geography: a North American/Caribbean clade and a South/Central American clade. We found considerable variation among regions of the mitochondrial genome in both substitution rates and the level of information that each region supplied for phylogenetic reconstruction. We found no evidence of positive directional selection within mitochondrial coding regions, but we identified numerous sites under purifying selection. This finding suggests that, despite differences in life history traits and distributions, mitochondrial genes in Tachycineta are predominantly under purifying selection for conserved function.

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► We present a tree for Tachycineta swallows from complete mitochondrial genomes.
► MtDNA genes differed in substitution rates and amount of phylogenetic information.
► We found no evidence of directional selection across any mitochondrial region.